In the pressure impregnation of porous ceramic parts with metal one uses for example lead or lead alloys. These materials are known to have no wetting action on ceramic surfaces. After the pressure impregnation, therefore, the liquid metal can run out of the components again when the ceramic parts are extracted from the impregnating bath. To prevent this, normally the outer surfaces of the ceramic part are coated with fine-pored coatings, e.g. by sintering on glass frits, which after pressure impregnation must be removed mechanically, or by the firing on of silver pastes.
In U.S. Pat. Nos. 3,965,552 and 4,071,880 a filler layer component of the above mentioned kind and a method for the production thereof are known, wherein the layer structure of alternately dense and porous layers is impregnated, in particular with the metals lead (Pb), aluminum (Al), copper (Cu), zinc (Zn), tin (Sn) and cadmium (Cd) or alloys of one or more of these metals. The assumption here is that specifically those metals must be selected which do not wet the ceramic bodies into which they are being injected. In particular, undesirable surface depositions of the metals or of the alloys are to be prevented or minimized as they would otherwise have to be removed separately in order to prevent short ciruits. Specifically there is proposed in the above identified U.S. Patent that the bismuth alloy Bi63Pb25Sn10In2, the zinc alloy ZnAl4Cu1 or the silver alloy AgCu28 as well as various brasses and bronzes, which are said to fulfill the stipulated limit conditions.
It is therefore an object of the present invention to develop filler layer components with their respective impregnating materials for which no additional measures are necessary to prevent the melt from running out of the ceramic part when it is being extracted from the impregnating bath.